For example, a semiconductor storage device which stores information by changing the resistance of a storage layer has been proposed. A phase-change random access memory (PcRAM) is known as an example of the semiconductor storage device. The phase-change random access memory stores information by applying current or voltage to a memory element formed of a phase-change material and changing the memory element to an amorphous phase showing a high resistance or a crystalline phase showing a low resistance.
In a write cycle of the phase-change memory, due to relationships in voltage among a selected bit line, a selected word line, a non-selected bit line and a non-selected word, write disturb occurs in a non-selected cell and a half-selected cell which is slightly selected. However, if current or voltage to the selected cell is reduced for the sake of preventing write disturb, a write error occurs in the selected cell. Therefore, there has been a demand for a semiconductor storage device which can prevent write disturb in a non-selected cell and a half-selected cell and can also prevent a write error in a selected cell.